package Perl::Critic::Policy::BuiltinFunctions::ProhibitUniversalIsa;

use 5.006001;
use strict;
use warnings;
use Readonly;

use Perl::Critic::Utils qw{ :severities :classification };
use base 'Perl::Critic::Policy';

our $VERSION = '1.134';

#-----------------------------------------------------------------------------

Readonly::Scalar my $DESC => q{UNIVERSAL::isa should not be used as a function};
Readonly::Scalar my $EXPL => q{Use eval{$obj->isa($pkg)} instead};  ## no critic (RequireInterp);

#-----------------------------------------------------------------------------

sub supported_parameters { return ()                     }
sub default_severity     { return $SEVERITY_MEDIUM       }
sub default_themes       { return qw( core maintenance certrule ) }
sub applies_to           { return 'PPI::Token::Word'     }

#-----------------------------------------------------------------------------

sub violates {
    my ( $self, $elem, undef ) = @_;
    return if !($elem eq 'isa' || $elem eq 'UNIVERSAL::isa');
    return if ! is_function_call($elem); # this also permits 'use UNIVERSAL::isa;'

    return $self->violation( $DESC, $EXPL, $elem );
}


1;

__END__

#-----------------------------------------------------------------------------

=pod

=head1 NAME

Perl::Critic::Policy::BuiltinFunctions::ProhibitUniversalIsa - Write C<< eval { $foo->isa($pkg) } >> instead of C<UNIVERSAL::isa($foo, $pkg)>.


=head1 AFFILIATION

This Policy is part of the core L<Perl::Critic|Perl::Critic>
distribution.


=head1 DESCRIPTION

    print UNIVERSAL::isa($obj, 'Foo::Bar') ? 'yes' : 'no';  #not ok
    print eval { $obj->isa('Foo::Bar') } ? 'yes' : 'no';    #ok

As of Perl 5.9.3, the use of C<UNIVERSAL::isa> as a function has been
deprecated and the method form is preferred instead.  Formerly, the
functional form was recommended because it gave valid results even
when the object was C<undef> or an unblessed scalar.  However, the
functional form makes it impossible for packages to override C<isa()>,
a technique which is crucial for implementing mock objects and some
facades.

Another alternative to UNIVERSAL::isa is the C<_INSTANCE> method of
Param::Util, which is faster.

See the CPAN module L<UNIVERSAL::isa|UNIVERSAL::isa> for an incendiary
discussion of this topic.


=head1 CONFIGURATION

This Policy is not configurable except for the standard options.


=head1 SEE ALSO

L<Perl::Critic::Policy::BuiltinFunctions::ProhibitUniversalCan|Perl::Critic::Policy::BuiltinFunctions::ProhibitUniversalCan>

=head1 AUTHOR

Chris Dolan <cdolan@cpan.org>

=head1 COPYRIGHT

Copyright (c) 2006-2011 Chris Dolan.

This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.  The full text of this license
can be found in the LICENSE file included with this module.

=cut

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